iirc as a human you can take the huntsmaster feat, which treats you as +1 level for your companion's stuff, and it applies to birds (as well as horses, dogs, and another that slips my mind). it also grants handle animal bonuses for the selected animal, but that is slightly less important.

And that AOO prevention is the whole point with a fragile Animal Companion.

Flyby Attack (Monster)

This creature can make an attack before and after it moves while flying.

Prerequisite: Fly speed.

Benefit: When flying, the creature can take a move action and another standard action at any point during the move. The creature cannot take a second move action during a round when it makes a flyby attack.

Normal: Without this feat, the creature takes a standard action either before or after its move.

Using the chain I outlined before, your critter can dive bomb in, with a good chance of hitting, and then be back in the air with out taking a hit.
And you get a spiffy +1 AC against any and all pesky attacks AND if anything ever gets close you can have your critter retreat/attack someone else with additional +4 to AC vs that AOO.

Flyby attack CAN do the same but that AOO can take them out pretty quickly.

If its a Ranger's bird, it has the advantage of sharing his Favored Enemy bonus's, which can make it pretty crazy. Couple that with a Aasimar who uses the Celestial Servant feat to give it smite...you wouldn't have to worry much about the foe being there to retaliate.

Definitely build with Weapon Finesse and Agile AoMF. I'm also a big fan of custom barding(ex:mithril chain shirt), built such that it has no Armor check penalty, allowing them to use it without proficiency and no negatives.

I had a Druid with a bird, but I focused it into a Stealth/Disarm machine, which ended up being hilarious cause it'd snatch a foes weapon, then fly into some cover and disappear.

Forgot about the custom barding, thats a good tip! I'll have to try and sneak Celestial in there for the DR10/evil and Smite as well. And SR... how does this only cost one feat?!

I'd love to go the disarm route, but I'd be scared of getting the thing killed when it provokes an attack every time (animals can't get combat expertise, not even close to enough Int!)

The character I'm specifically building with an animal companion is SGG's Magister, which I'm using to build an homage to the Fochlucan Lyrist (3.5, CA). So no ranger stuff, no archery.

Caster with an animal companion, pewpew. Investing 3 feats (Magister Companion, Boon Companion, and Celestial Servant) so it better be worth it :) Might even take Huntmaster if I have room in my build (which is not looking good).

Not really a fan of Death From Above, 1 feat to give +3 on an aerial charge.. /shrug. It's attack bonus should be good enough with Greater Magic Fang.

would spring attack stop the rider from provoking if the animal companion is using the feat? how would that work? i would think a rider would provoke normally in that case, if so is there any way to stop it? i wouldn't think RAW would allow the rider to use his own spring attack simultaneously, if he had it

And that AOO prevention is the whole point with a fragile Animal Companion.

Flyby Attack (Monster)

This creature can make an attack before and after it moves while flying.

Prerequisite: Fly speed.

Benefit: When flying, the creature can take a move action and another standard action at any point during the move. The creature cannot take a second move action during a round when it makes a flyby attack.

Normal: Without this feat, the creature takes a standard action either before or after its move.

#1: At 4th level, us the option to take +2 Dex & Con instead of the listed upgrade. Sticking with that means weapon finesse stays good and you just get more AC / Initiative & reflex for your evasion. Net attack roll goes up instead of down ;-)

ALSO...

#2: Get it an Agile Amulet of Mighty Fists (4k gp), it will now add its Dex to damage instead of strength (should be a +5 dex mod or more by 4th, if you follow advice #1 above.)

#3: Consider being human, and taking the "Eye for Talent" alternate racial ability --gives up your bonus feat for +2 Dex to your bird, and you get a bonus on Sense Motive or something. That's another +1 to hit / ac / reflex / initiative / dmg (with Agile).

OR it could be +2 Int to start with an Int of 4... that's 6 more Tricks, and you can have your bird take -any- feat from level 1... How about juicy ones like Death From Above? Additional Traits? Flanking Foil? etc...

Hunter dip 2 levels: May seem redundant but a free Precise Shot feat for you (if ranged) or Outflank for both you and Bird (if melee) is nice, and so is ability to give your bird +2 all day to any physical stay, and hey also you get Resist Energy as a 1st level spell --bonus! Also, if you do this you can use some of your animal's tricks to teach it special Skirmisher Ranger abilities... like Entangling Strike, Tripping Strike, etc... That's pretty boss.

ALSO If you push Hunter to 3rd level you get more options like either Teamwork feats with Bird or the Divine Hunter archtype: So humans can now make bird celestial anyway (and still get their +2 bird stat from Eye for Talent), OR, Aasimar can use Celestial Servant to make bird Celestial AND ALSO use Divine Hunter 3rd to make Bird Fiendish at same time... crazy but legal RAW. So bird now has scaling resist to all 4 elements and his DR is both Good & Evil (aka +5 weapon or Smite is only way past his DR.)

OTHER IDEA: Another wierd dip is Huntmaster Cavalier. At 3rd level their Bird gets to make free Dirty Trick checks on every attack, from a limited set: Deafened or Dazzled, but, if target already Dazzled (say from your Death from Above partial charge in the Surprise round) then bird can do Blinded.

...That's strong. Especially if they also have Skirmisher tricks like Entangle and Trip. That means at 4th level, in round 1 or 2 of combat the bird has made 1 target Blind, Deaf, Dazzled, Tripped and Entangled off of 3 or 4 attacks. And done damage 1d3/4 +5 or +6 like 3 or 4 times. That makes the summoner's Eidolon look like a chode, and the other druid's boring Big Cat look like a Big P__sy. lol...

#5: Feats & Traits:

Trait: Blackthorn Rancher (regional). Take this to give your bird +3 Hp at 1st level. Gives you bonus to handle Animal as well.

Trait: Deadeye Bowman. Take this (and worship Erastil) to ignore soft cover from your Bird or your party meat shield... err... fighter, so you can shoot lots of Abundant Ammo Trip Arrows, Tangleshot Arrows and maybe even Pheromone Arrows (if anyone in your party has Scent) from a safe distance, without the Pesky -4 to hit. Works best paired with Precise Shot from Hunter 2nd.

Feat: Andoran Falconry (aka Master of Falcons). Requires Animal Affinity (sigh) but gives choice of bonuses to Bird. Best: +2 morale to Will saves if you took Totem Guide (since Bird lost Devotion in that case), or, +1 morale to attack rolls... IF you then give Bird Additional Traits feat and give it trait: Adopted: Half Orc (menacing or whatever it's called racial trait that adds +1 to damage whenever you have morale bonus for attacking... which is 100% of the time for your bird ;-)

Spirits Gift (non PFS only): Best feat for anyone with an animal companion. Probably use the DR 5 option most days at low level, though the 24 hours Blur is great too if you have Bird invest in stealth (effectively Hide in Plain Sight... yes, it's true, with 1 feat you take your Bird becomes a better Shadow dancer than the damned prestige class.)

Evolved Companion (non-PFS again): this breaks the game. Avoid it unless you need revenge on a sh__-talking melee party member or whatever... in which case, reach on you bird is nice, as are all the other broken summoner options.